Bridge characterization and structural health monitoring: a suspension bridge case study

Detecting and assessing the severity of structural damage is one major objective when monitoring a bridge. In particular, when some degradation phenomena threaten the bridge safety, the goal can be to assess monitoring critical components, which allows checking a safety threshold is not reached until some repair/rehabilitation actions are performed. This paper describes an overall monitoring-based decision process, illustrated with the case of a suspension bridge in France, the Teil Bridge near Montelimar. Following the sudden fracture of a cable near the anchorage, the bridge was totally closed to traffic. Several investigations were carried out to better understand the reason of the fracture occurrence and assess the performance of other anchorages. The bridge safety was ensured by strengthening each anchorage, starting an acoustic monitoring program (during one year), and defining warning thresholds. Meanwhile, several other experimental investigations (in situ load tests, chemical analysis of concrete samples) were conducted to estimate the residual structural service life and define the bridge repair actions. Finally, a major rehabilitation program with the change of all cables and anchorages was decided. The example of the Teil Bridge illustrates the progress of monitoring information integration in a bridge management system.